This invention relates to a locking device for doors and the like, having sockets in the door frame and in the door, a bolt disposed within the socket of the frame and adapted to be displaceable partially into the socket of the door for the locking of the door, and actuating means consisting of electrical and/or mechanical means for moving the bolt into the open position and of a spring for moving the bolt into the shut position.
In conventional locks, the bolt is provided in the door, and in a locking situation it will be pushed into the socket of the frame. Locks are also previously known wherein the bolt is provided in the frame. Since in that case there is very little room for mechanical actuators, the bolts are generally electrically operated. In these cases, the rear end of the bolt is encased by a solenoid connected to a power supply and e.g. to a code key.
Safety regulations require that the door can be opened from the inside also mechanically. Since installing a mechanical actuator in the frame to be in connection with a journalled bolt will present problems owing to the lack of space, the use of locking devices of this kind has not become more prevalent, even though they have some significant advantages, including the safe placement of the device within the wall and the absence of a transmission cable between the door and the frame.